来源: https://www.avanderlee.com/swiftui/integrating-swiftui-with-uikit/

在HWS中学到了怎么在SwiftUI中使用UIKit，那么快来学一下怎么使用SwiftUI吧

在SwiftUI中定义了一个Controller名字叫UIHostingController，介绍就是A UIKit view controller that manages a SwiftUI view hierarchy.

那就直接拿来用就行，使用Push或者Present都是可行的。

这里先创建了一个SwiftUIView

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func presentSwiftUIView() {
    let swiftUIView = SwiftUIView()
    let hostingController = UIHostingController(rootView: swiftUIView)
//        present(hostingController, animated: true, completion: nil)
    navigationController?.pushViewController(hostingController, animated: true)
}

Dec-01-2020 22-14-31功能也是完整的。但是如果要直接在当前的Controller上显示呢？

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func addSwiftUIView() {
    let swiftUIView = SwiftUIView()
    let hostingController = UIHostingController(rootView: swiftUIView)

    /// Add as a child of the current view controller.
    addChild(hostingController)

    /// Add the SwiftUI view to the view controller view hierarchy.
    view.addSubview(hostingController.view)

    /// Setup the constraints to update the SwiftUI view boundaries.
    hostingController.view.translatesAutoresizingMaskIntoConstraints = false
    let constraints = [
        hostingController.view.topAnchor.constraint(equalTo: view.topAnchor),
        hostingController.view.leftAnchor.constraint(equalTo: view.leftAnchor),
        view.bottomAnchor.constraint(equalTo: hostingController.view.bottomAnchor),
        view.rightAnchor.constraint(equalTo: hostingController.view.rightAnchor)
    ]

    NSLayoutConstraint.activate(constraints)

    /// Notify the hosting controller that it has been moved to the current view controller.
    hostingController.didMove(toParent: self)
}

Dec-01-2020 22-14-31还可以改成泛型的代码

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extension UIViewController {

    /// Add a SwiftUI `View` as a child of the input `UIView`.
    /// - Parameters:
    ///   - swiftUIView: The SwiftUI `View` to add as a child.
    ///   - view: The `UIView` instance to which the view should be added.
    func addSubSwiftUIView<Content>(_ swiftUIView: Content, to view: UIView) where Content : View {
        let hostingController = UIHostingController(rootView: swiftUIView)

        /// Add as a child of the current view controller.
        addChild(hostingController)

        /// Add the SwiftUI view to the view controller view hierarchy.
        view.addSubview(hostingController.view)

        /// Setup the contraints to update the SwiftUI view boundaries.
        hostingController.view.translatesAutoresizingMaskIntoConstraints = false
        let constraints = [
            hostingController.view.topAnchor.constraint(equalTo: view.topAnchor),
            hostingController.view.leftAnchor.constraint(equalTo: view.leftAnchor),
            view.bottomAnchor.constraint(equalTo: hostingController.view.bottomAnchor),
            view.rightAnchor.constraint(equalTo: hostingController.view.rightAnchor)
        ]

        NSLayoutConstraint.activate(constraints)

        /// Notify the hosting controller that it has been moved to the current view controller.
        hostingController.didMove(toParent: self)
    }
}